On July 22, 2011, NASA announced that the Curiosity rover will target Gale Crater as its landing site. The rover will explore the lower portion of a 5-km mound of stratified materials located inside the crater. Variations in texture and mineralogy among the strata suggest that the materials contain a record of major climatic changes in Mars' history. Curiosity will arrive at Gale Crater on August 5, just after 10 pm Pacific time. The following paragraphs describe the site selection process that occurred from 2006 to 2011.

The MSL landing site will profoundly influence the nature and quality of the scientific return from the mission, as well as the pace and strategy for surface operations. An ideal landing site would: i) contain evidence suggestive of a past or present habitable environment; ii) meet or exceed all engineering and safety constraints; and iii) allow acceptable operational performance. A corollary to the first criterion is that the evidence for habitability, whether geological, chemical, or biological, would be preserved for, accessible to, and interpretable by the MSL payload. Operational performance can be impacted by terrain (e.g., more obstacles to navigate through) or temperatures (e.g., colder daytime temperatures result in energy being diverted to heaters).

The selection of the MSL landing site is informed through a series of community-led, open workshops that have occurred in parallel with the design and development of the spacecraft. The workshops are organized by a NASA-appointed Landing Site Steering Committee, co-chaired by Dr. John Grant (Smithsonian Institution) and Dr. Matthew Golombek (JPL). Workshops in June 2006, October 2007, September 2008, September 2010, and May 2011 considered over sixty sites, narrowing the list of candidate sites to four. The down-selections have been based on many factors including their scientific relevance and assessment against surface and atmospheric safety constraints. The final site was selected in July, 2011 after the final community workshop and subsequent analyses by the MSL Project, science teams, and NASA officials.

One of the programmatic goals of the MSL mission is to provide access to more of Mars´ surface by removing or broadening the constraints present on previous missions and by not tailoring the design to any specific site or set of environmental conditions. Such a design also allows the final site selection to occur later in the process, providing more time to incorporate data and discoveries from the missions that precede MSL. Relative to previous landers, MSL can target a site with smaller uncertainty (25 x 20 km landing error ellipse) and can land and operate over a wider range of latitudes (i.e., thermal environments) and elevations. In addition, the rover´s driving capability is similar to its landing uncertainty, meaning that the rover can drive outside of its error ellipse. This factor allows the exploration of regions that extend beyond the area safe for landing. All of the candidate landing sites contain features of interest both inside and beyond the bounds of the landing ellipse.

A list of the current candidate landing sites can be found below. These finalist sites have passed preliminary checks against engineering and safety criteria, though data acquisition and analyses are ongoing. From a scientific standpoint, sites with mineralogical (phyllosilicates or sulfates) and/or geological evidence (depositional fans, fluvial systems) for past aqueous activity, as detected from orbit, are thought to be the most relevant for the MSL science objectives and payload.

Name

Location

Elevation

Eberswalde Crater

23.90S, 326.74E

-1435 m

Gale Crater

4.49S, 137.42E

-4444 m

Holden Crater

26.40S, 325.16E

-2177 m

Mawrth Vallis

23.99N, 341.04E

-2245 m

Landing will occur in the mid-afternoon, in late northern Summer at Ls=151. Landing site safety criteria, EDL capabilities, and ellipse parameters are described in the first web link below. The links also contain the presentations from the community workshops, and catalogs of the data sets from various orbital experiments that are relevant to site studies.